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Handle improperly aligned stack pointers more cleanly.

This commit is contained in:
eeh 2002-06-05 18:11:18 +00:00
parent 7a79aa5e02
commit e7fe9c7c35
1 changed files with 60 additions and 15 deletions
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75
sys/arch/sparc64/sparc64/locore.s
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@ -1,4 +1,4 @@
/* $NetBSD: locore.s,v 1.155 2002/06/04 15:04:08 eeh Exp $ */
/* $NetBSD: locore.s,v 1.156 2002/06/05 18:11:18 eeh Exp $ */
/*
* Copyright (c) 1996-2002 Eduardo Horvath
@ -3422,9 +3422,17 @@ fp_exception:
/*
* We're here because we took an alignment fault in NUCLEUS context.
* This could be a kernel bug or it could be due to saving a user
* window to an invalid stack pointer. If the latter is the case,
* we should emulate the save by storing all the user register windows
* to the PCB and returning.
* window to an invalid stack pointer.
*
* If the latter is the case, we could try to emulate unaligned accesses,
* but we really don't know where to store the registers since we can't
* determine if there's a stack bias. Or we could store all the regs
* into the PCB and punt, until the user program uses up all the CPU's
* register windows and we run out of places to store them. So for
* simplicity we'll just blow them away and enter the trap code which
* will generate a bus error. Debugging the problem will be a bit
* complicated since lots of register windows will be lost, but what
* can we do?
*/
checkalign:
rdpr %tl, %g2
@ -3448,8 +3456,8 @@ checkalign:
!!
!! Double data fault -- bad stack?
!!
wrpr %g2, %tl ! Restore trap level.
sir ! Just issue a reset and don't try to recover.
wrpr %g2, %tl ! Restore trap level.
sir ! Just issue a reset and don't try to recover.
mov %fp, %l6 ! Save the frame pointer
set EINTSTACK+USPACE+CC64FSZ-STKB, %fp ! Set the frame pointer to the middle of the idle stack
add %fp, -CC64FSZ, %sp ! Create a stackframe
@ -3459,17 +3467,54 @@ checkalign:
ba slowtrap ! all our register windows.
wrpr %g0, 0x101, %tt
#endif
checkalignspill:
wr %g0, ASI_DMMU, %asi ! We need to re-load trap info
ldxa [SFSR] %asi, %g3 ! get sync fault status register
stxa %g0, [SFSR] %asi ! Clear out fault now
membar #Sync ! No real reason for this XXXX
checkalignspill:
/*
* Here we just jump to winfixspill and let it take care of
* saving the windows.
* %g1 -- current tl
* %g2 -- original tl
* %g4 -- tstate
* %g7 -- tt
*/
ba,pt %icc, winfixspill ! Continue with the winfix
orcc %g0, %g0, %g0 ! Make sure we compare to zero
and %g4, CWP, %g5
wrpr %g5, %cwp ! Go back to the original register win
/*
* Remember:
*
* %otherwin = 0
* %cansave = NWINDOWS - 2 - %canrestore
*/
rdpr %otherwin, %g6
rdpr %canrestore, %g3
rdpr %ver, %g5
sub %g3, %g6, %g3 ! Calculate %canrestore - %g7
and %g5, CWP, %g5 ! NWINDOWS-1
movrlz %g3, %g0, %g3 ! Clamp at zero
wrpr %g0, 0, %otherwin
wrpr %g3, 0, %canrestore ! This is the new canrestore
dec %g5 ! NWINDOWS-2
wrpr %g5, 0, %cleanwin ! Set cleanwin to max, since we're in-kernel
sub %g5, %g3, %g5 ! NWINDOWS-2-%canrestore
#ifdef xTRAPTRACE
wrpr %g5, 0, %cleanwin ! Force cleanwindow faults
#endif
wrpr %g5, 0, %cansave
wrpr %g0, T_ALIGN, %tt ! This was an alignment fault
/*
* Now we need to determine if this was a userland store or not.
* Userland stores occur in anything other than the kernel spill
* handlers (trap type 09x).
*/
and %g7, 0xff0, %g5
cmp %g5, 0x90
bz,pn %icc, slowtrap
nop
bclr TSTATE_PRIV, %g4
wrpr %g4, 0, %tstate
ba,a,pt %icc, slowtrap
nop
/*
* slowtrap() builds a trap frame and calls trap().